[DeTomaso] Unhappy motor - looking for suggestions

Pantdino pantdino at aol.com
Sun Nov 2 14:36:24 EST 2014


Sounds like a carburetor problem to me. 
Does it idle OK?  If so, the idle circuit is OK but the main circuit and /or acceleration circuits might have a problem
 
When you add throttle the carb has to allow more fuel in. If a jet is clogged it doesn't and the engine goes lean and stumbles. Does it help if you pump the gas pedal?  That pumps in fuel from the acceleration circuit to richen the mixture.


Carbs have idle, main /cruise, and acceleration circuits, and any one or all can develop problems. My wife's Chevy once developed a problem where it idled fine but you basically had to pump the throttle constantly to make the car go. Rebuilding the carb solved the problem.

Jim Oddie

-----Original Message-----
From: Charles McCall <charlesmccall at gmail.com>
To: 'thomas' <thomas at hax.se>
Cc: detomaso <detomaso at poca.com>
Sent: Sun, Nov 2, 2014 11:20 am
Subject: Re: [DeTomaso] Unhappy motor - looking for suggestions


I haven't checked timing, but wouldn't that make the engine run hot? 

Would that explain the stumble? It might explain why it doesn't feel as
crisp as it should

-----Original Message-----
From: thomas [mailto:thomas at hax.se] 
Sent: domingo, 2 de noviembre de 2014 20:18
To: Charles McCall
Cc: <detomaso at poca.com>
Subject: Re: [DeTomaso] Unhappy motor - looking for suggestions

The distributor gear pin?

Checked timing?


> 2 nov 2014 kl. 20:13 skrev Charles McCall <charlesmccall at gmail.com>:
> 
>   Hi all
> 
> 
>   I just got back from a Supercar event in northern Spain with 35 cars
>   attending - Lambo, Ferrari, Viper, Porsche, and, as usual, a lone
>   DeTomaso!
> 
> 
>   The highlight for me without a doubt was an 8-minute burst on the
>   highway with the police clearing the way for us, cruising at a steady
>   GPS-indicated 180 k/hr in a 35 car convoy... the people out for a
>   Sunday drive must have had their minds boggled...
> 
> 
>   Anyway, my engine is not happy. This morning in the hotel parking lot I
>   really thought that we'd have to skip today's event because it wouldn't
>   start and didn't sound like it was even thinking about starting. Took
>   probably 5 minutes of crank-wait-crank-wait before it fired. Yesterday
>   at the gas station it took 2-3 minutes to start, something that has
>   never, ever happened before. It is really hard to describe the problem
>   so much of it is "feel", but I'll do my best.
> 
> 
>   A few weeks ago I noticed that the engine would tend to stumble if I
>   would floor the throttle, then clear its throat and pull. For example,
>   I like to heel-and-toe, just because, and when blipping the throttle it
>   would stumble instead of rev. The engine also felt a little rougher, as
>   though it vibrated more than I remembered it. I don't remember if this
>   was before or after I did a short tune-up, by adjusting the valve lash
>   (I have mechanical lifters), and cleaning the K&N air filter by
>   applying K&N filter oil, etc. or if it is irrelevant. So I was messing
>   around in the engine bay recently...
> 
> 
>   This weekend the engine felt considerably worse. It felt like it would
>   stumble under partial throttle as well. It would stumble a little bit
>   under trailing throttle going downhill as well, so I don't think it is
>   a clogged fuel filter.
> 
> 
>   Oil temp is perfect. Oil pressure is perfect. Water temp is perfect.
>   The engine idles perfectly. But if you floor the gas from idle, it'll
>   stall. The engine doesn't feel crisp, it feels bloated and soft, if
>   that makes sense. It feels rough, and it feels like it occasionally
>   stumbles under constant throttle at highway speed. It pulls hard when
>   accelerating, but I don't think as hard as it used to, or as high (I
>   have a 6500 rpm limiting chip in the MSD that it used to pull very
>   easily to).
> 
> 
>   Suggestions for where to begin looking? And other info that would help
>   in troubleshooting?
> 
> 
> !DSPAM:54568258260291209923907!
> _______________________________________________
> 
> Detomaso Forum Managed by POCA
> 
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> 
> 
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-------------- next part --------------
   Sounds like a carburetor problem to me.

   Does it idle OK?  If so, the idle circuit is OK but the main circuit
   and /or acceleration circuits might have a problem



   When you add throttle the carb has to allow more fuel in. If a jet is
   clogged it doesn't and the engine goes lean and stumbles. Does it help
   if you pump the gas pedal?  That pumps in fuel from the acceleration
   circuit to richen the mixture.





   Carbs have idle, main /cruise, and acceleration circuits, and any one
   or all can develop problems. My wife's Chevy once developed a problem
   where it idled fine but you basically had to pump the throttle
   constantly to make the car go. Rebuilding the carb solved the problem.



   Jim Oddie



   -----Original Message-----
   From: Charles McCall <charlesmccall at gmail.com>
   To: 'thomas' <thomas at hax.se>
   Cc: detomaso <detomaso at poca.com>
   Sent: Sun, Nov 2, 2014 11:20 am
   Subject: Re: [DeTomaso] Unhappy motor - looking for suggestions
I haven't checked timing, but wouldn't that make the engine run hot?

Would that explain the stumble? It might explain why it doesn't feel as
crisp as it should

-----Original Message-----
From: thomas [[1]mailto:thomas at hax.se]
Sent: domingo, 2 de noviembre de 2014 20:18
To: Charles McCall
Cc: <[2]detomaso at poca.com>
Subject: Re: [DeTomaso] Unhappy motor - looking for suggestions

The distributor gear pin?

Checked timing?


> 2 nov 2014 kl. 20:13 skrev Charles McCall <[3]charlesmccall at gmail.com>:
>
>   Hi all
>
>
>   I just got back from a Supercar event in northern Spain with 35 cars
>   attending - Lambo, Ferrari, Viper, Porsche, and, as usual, a lone
>   DeTomaso!
>
>
>   The highlight for me without a doubt was an 8-minute burst on the
>   highway with the police clearing the way for us, cruising at a steady
>   GPS-indicated 180 k/hr in a 35 car convoy... the people out for a
>   Sunday drive must have had their minds boggled...
>
>
>   Anyway, my engine is not happy. This morning in the hotel parking lot I
>   really thought that we'd have to skip today's event because it wouldn't
>   start and didn't sound like it was even thinking about starting. Took
>   probably 5 minutes of crank-wait-crank-wait before it fired. Yesterday
>   at the gas station it took 2-3 minutes to start, something that has
>   never, ever happened before. It is really hard to describe the problem
>   so much of it is "feel", but I'll do my best.
>
>
>   A few weeks ago I noticed that the engine would tend to stumble if I
>   would floor the throttle, then clear its throat and pull. For example,
>   I like to heel-and-toe, just because, and when blipping the throttle it
>   would stumble instead of rev. The engine also felt a little rougher, as
>   though it vibrated more than I remembered it. I don't remember if this
>   was before or after I did a short tune-up, by adjusting the valve lash
>   (I have mechanical lifters), and cleaning the K&N air filter by
>   applying K&N filter oil, etc. or if it is irrelevant. So I was messing
>   around in the engine bay recently...
>
>
>   This weekend the engine felt considerably worse. It felt like it would
>   stumble under partial throttle as well. It would stumble a little bit
>   under trailing throttle going downhill as well, so I don't think it is
>   a clogged fuel filter.
>
>
>   Oil temp is perfect. Oil pressure is perfect. Water temp is perfect.
>   The engine idles perfectly. But if you floor the gas from idle, it'll
>   stall. The engine doesn't feel crisp, it feels bloated and soft, if
>   that makes sense. It feels rough, and it feels like it occasionally
>   stumbles under constant throttle at highway speed. It pulls hard when
>   accelerating, but I don't think as hard as it used to, or as high (I
>   have a 6500 rpm limiting chip in the MSD that it used to pull very
>   easily to).
>
>
>   Suggestions for where to begin looking? And other info that would help
>   in troubleshooting?
>
>
> !DSPAM:54568258260291209923907!
> _______________________________________________
>
> Detomaso Forum Managed by POCA
>
> DeTomaso mailing list
> [4]DeTomaso at poca.com
> [5]http://poca.com/mailman/listinfo/detomaso_poca.com
>
>
> !DSPAM:54568258260291209923907!


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References

   1. mailto:thomas at hax.se?
   2. mailto:detomaso at poca.com
   3. mailto:charlesmccall at gmail.com
   4. mailto:DeTomaso at poca.com
   5. http://poca.com/mailman/listinfo/detomaso_poca.com
   6. mailto:DeTomaso at poca.com
   7. http://poca.com/mailman/listinfo/detomaso_poca.com


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